Fetching from the wire…
Public story · 2026-09-09 · high
OpenAI won't say whether Codex chat data trained its models, and Willison says that leaves your unfinished work exposed.
Why now: Willison posted the piece on September 8, prompted by OpenAI's own admission about de-identified usage data.
Simon Willison is raising a specific worry about working inside AI coding tools. Your unsolved problem might help someone else solve it first.
The trigger is a line from OpenAI itself. The company says it "cannot rule out that de-identified data derived from their usage of our products helped improve our models." Willison lays that admission next to a case where mathematicians were drafting inside Codex sessions. In his Navier-Stokes post, he asks it plainly: if you're working through a hard, unsolved problem in a chat session, is that work feeding the model everyone else uses too?
That question matters most the closer your work sits to a real frontier. Most code written in an agent session isn't novel. But if you're drafting a proof, a new architecture, or an unpublished algorithm inside a hosted coding tool, the stakes are different.
Willison notes OpenAI declined to answer the direct question of whether that data trains future models. Not a denial, not a confirmation. Silence on the exact point that matters.
He isn't claiming OpenAI trained on any specific person's math. He's naming an incentive problem. The company benefits from staying vague. Users have no way to verify the boundary themselves.
Until a vendor states that boundary in specific terms, the assumption for original work drafted inside these tools stays the same: it may not be private.
Each link below shares sources, entities, or timing with this story.
Thibault Sottiaux at OpenAI published an investigation into "a handful of reports where GPT-5.6 unexpectedly deleted files," finding it happens most commonly when full access mode is enabled in Codex. Simon Willison relayed it. A frontier lab publishing a first-party post-mort...
Simon Willison spent a while taking ChatGPT Work apart and published the map on August 30. Work splits into Work Cloud and Work Local, the latter being the renamed Codex desktop app, at $20/month and up since July 9. He enumerates six capabilities Work has that Chat doesn't, a...
Spotify's Portal team published Xirp on August 10: a vendor-neutral agentic development environment that manages concurrent sessions across Claude Code, Gemini CLI, and Codex, each session isolated in its own git worktree so dozens of agents can work the same codebase without...
Willison's analysis of the Astral acquisition: uv and ruff are used by Anthropic, Google, and the entire Python community — tools now owned by a direct competitor. He calls it "genuinely surprising" and questions whether OpenAI can maintain open-source neutrality with strong i...
GPT-5.6 Luna went to $0.20 input / $1.20 output per million tokens on July 30. That's an 80% cut. Terra dropped 20%. Luna's input now undercuts Gemini 3.1 Flash-Lite ($0.25/$1.50) and sits at one-fifth of Claude Haiku 4.5's $1 input. Simon Willison covered the announcement and...
OpenAI announced March 19 it's acquiring Astral, the company behind uv (126M downloads/month), ruff (the Python linter/formatter), and ty (type checker). The team integrates into Codex. The strategic logic is explicit: move Codex beyond code generation into full-lifecycle deve...
MindPattern daily
One email a day at 7 AM. Sources and a take on every story. Unsubscribe anytime.